Manufacture of artificial filaments and the like



- Fish. 26, 1935. H. DREYFU-S MANUFACTURE OF ARTIFICIAL FILAMENTS ANDTHE LIKE Filed Aug. 26. 1952 inventor: HENRY DREYFUS b 3 W M m Ndormz 5Patented Feb. 26, 1935 PATENT mm:

. 1 MANUFACTURE OF ARTIFICIAL FILAMENTS AND THE LIKE Henry Dreyfus,London, England I v Application August 26, 1932, Serial No. 630,491 I IIn Great Britain October 7 21; Claims.

This invention relates to improvements in the manufacture of artificialsilk and like filaments, threads, yarns, ribbons and the like fromsolutions of cellulose acetate or other cellulose esters v or ethers bythe. dry spinning method.

The principal object of the invention is toobtain filaments or otherproducts of very high tenacity.

According to the present invention in the dry- The retardation of theevaporationin the.

initial stages of the spinning operation may be achieved by any suitablemethod. The methods described in U. S. application S. No. 561,442 filed5th September, 1931, are particularly important. This specificationdescribes inter aliathe provi- 25 sion around the spinning nozzle of a,pipe, tube or other device adapted to shield the filaments in theinitial stages of their formation from the evaporative medium in themain body of the spinning cell. By this means the space enclosed by thesaid pipe, tube or other device becomes saturated with the vapour of thesolvent of the spinningsolution or it may, if desired, be saturated bysuitable injection of such solvent and the evaporation of the solventfrom the filaments in the initial stages of their formation isconsiderably retarded or even prevented altogether. As described in thesaid specification a comparatively slow current of air may, if desired,be passed through such a funnel, pipe, tube or other device whichsecludes the spinning nozzles from the main spinning cell. Further ifdesired instead of providing such tube, pipe or the like surrounding thespinning nozzle a spinning chamber or cell may be divided into two ormore chambers, that adjacent the spinning nozzlebeing traversed at themost by only a slow current of evaporative medium or being provided froman outside source with vapours of the solvent of the spinning solution.r l

A further means of retarding the evaporation of the solvent in theinitial stages of spinning is that described in British application No.27,076 31 filed 29th September, 1931, namely by drawing off theevaporative medium from the spinning cell before said medium, reachesthe spinning nozzle, or, "in the case of'a co-current of evapora- A tivemedium, introducingsaid medium at some distancefrom the nozzle so. thatit does not contact therewith. V

' .A still further means of retarding the evaporation consists inincorporating in the spinning so' lution one or more high'boilingsolvents, or dil-. uents, and in this connection referenceis made to U.S. Patents Nos-1,616,787 and 1,566,384, and U. S. applicationsS. Nos.328,305 filed 24th December, 1928, 444,621 filed 15th April, 1930,522,530 filed 13th March, 1931, and 535,284 filed 5th'May, 19,31. Suchhigh boiling solvent or diluent may be incorporated in the spinningsolution in any desired proportion suitablefor retarding the evaporationof .the volatile solvent in the initialstages or suitablefor;maintaining the filaments or other products soft: Preferably theproportion of high boiling solvent does not exceed'100% of the weightof, the cellulose acetate or other cellulose derivative. In connectionwith the employment of suchhigh boiling solvents, it may be pointed out:that the'solvents which are most valuable are-those which yieldsolutions of the celluloseacetate or other base ofthespinning solutionwhich are of substantially higher viscosity-than are the correspondingsolutions in the volatile solvent itself. Thus; for instance, in

spinning a solution of cellulose acetate inacetone highlyvaluable'results are achieved by employing solvents which" yield asolution of cellulose acetate of at least 4, and preferably '6 to 10,times or more the viscosity of the corresponding solution of thecellulose acetate inacetone. The employment of suchhigh boiling solventsin the spinning solution is claimed broadly in .British application No.27324/31 filed 1st October, 1931. Examples of such high boiling solventsare mono-acetin, diacetin and glycolrmono-acetate', methyl glycolacetate, methyl'glycol dioxane, andj dimethylene dioxide. The firstthree of these solvents are especially valuable and yield solu-' tionsof cellulose acetate of exceedingly high .vis cosity. In some cases thesolvent need not yield a true solutionof the cellulose acetate but itshould preferablyyield a true solution on addi-. tion of a small amountof another agent, and particularly another solvent, such as acetone.

The present invention furthermore comprises the employment 'inconjunction with-one another of anytwo or more of the above means forretarding the evaporation. I

As previously indicated it is characteristic of the'present inventionthat in addition to retard ing the. evaporation of'the solvent in theinitial stages of spinning, the filaments, threads or the like arestretched in such a manner that the whole of the stretch does not runback to the spinning nozzle. This result may be brought about by anysuitable means. For example, in carrying out the invention the filamentsmay encounter means such as a roller, guide or tension device whichoffers a resistanceto their passage, the amount of the resistancedetermining whether tension applied to the softened portion of thefilaments is in part allowed to extend to the nozzle or is whollyconfined to a later stage of the drying. p

I find it desirable to employ in the spinning cell at least two rollers,preferably small, between which stretch or additional stretch isapplied. If desired three, four or morerollersor similar devices may beemployed so as to obtain a number of stretching stages. Such rollers maybe mounted on ball hearings or other anti-friction bearings so as tofacilitate' rotation. Two rollers between whichstretch or additionalstretchis applied to the filaments may differ. in diameter. The rollersmay be constructed of very light material, as for example of aluminiumor other light metal, or of insoluble phenol-aldehyde synthetic resin orother'resi'stant plastic material. Furthermore the'rollers maybe maderelatively short and mayif desiredbe grooved so as to receive thefilaments. Preferably such rollers are provided with means adapted toresist rotation thereof, such resistance differing'from roller toroller; Thus, for instance, the rollers may carry vanes or like devicesadapted to provide an air or liquid resistance'to the rotation of theroller'by rotating in a compartment outside the spinning cell orinside'the spinning cell and separated from the main body of the cell.Any othermeans may beadopted so as 'to set up in the rollers adifierential resistance to rotation, orthe rollers may be positivelydriven at different speeds, the roller nearest the jet beingrotated at aspeed calculated to impart little or no stretch to the filaments betweenit and the jet.

The filaments may be further stretched if desired after they haveleftthe spinning cell, such stretchbeing facilitated, if desiredorrequisite, by suitable application'of a solvent or softener.

Though the invention is especially of value in the spinning of filamentsor other'products of cellulose acetate, it may alsoibev applied to thespinning of solutions of. other: cellulose esters, as for examplecellulose formate, cellulose propionate, cellulose butyrate, cellulosenitrate or nitro-acetate, and of cellulose ethers, for instance methylcellulose, ethyl cellulose or benzyl cellulose. a

r The invention will now be described in greater detail with referenceto the'accompanying draw-' ing, but itis to be understood that thisdescription isigiven' byway of illustration only, and is in norespectlimitative. a r

Figure 1 is a side elevationin'section of a spinningcell for carryingout the present invention,

Figure 2shows a variation in detail of Figure 1,

Figures 3,4.and 5 show three further forms of apparatus for carrying outthe invention,'and- Figure 6 shows a variation indetail ofFigure5. H r vIn Figure 1a spinning cell.10 is 'providedwith pipev 11. for the supplyof spinning solution, pipe 11 leading the solution through a filtercandle 12 to aspinning jet 13. The:filaments 14 issuing from the jetpass in and out of a number of tensionrods15 and down the spinning cell10, turning at the bottom of the cell around a guide rod 16 and leavingthe cell through an aperture 17. A current of evaporative medium entersthe cell 10 at thebottom by an inlet 18 controlled by a cock 19 andleaves by a draw-off pipe 21 conveying it to a header 22, valve means 23being provided in order that the rate of flow of evaporative medium mayreadily be adjusted. A flow-gauge 24 mayjif desired, be connectedinthepipe 21.

In order that evaporation of the filaments 14 in the neighbourhood ofthe pipe 13 may be retarded, the jet 13 and the filaments 14 as far downas the rods 15 are surrounded by a cowl which is made in two parts 26,27 which may be telescoped and slid up the candle 12, by which they aresupported, when it is desired to reach the jet 13. In this manner thezone is kept more or less stagnant within-the hood, and the evaporationof solvent from the filaments between the jet l3 and rods 15 isretarded.

The filaments'l-leaving the cell 10 by the aperture 17* pass over asmall roller 28- freely rotating, preferably in ball bearings, inatrough 29 containing a liquid 30 which is a solvent, sof- 'tener, orgelling 'agentfor the substance of the filaments. The filaments 14 then:pass successively over two rollers 31, 32, the roller 31 rotating atsuch a speed as to stretch the filaments within the" cell 10, while theroller 32 rotates at a higherspe'ed in order'to stretch thefila'mentswhich, after setting in the cell 10, have been softenedtin passing overthe roller 28, between the rollers 31, 32. The stretch imparted by theroller 31 extends asfar as thetension rods 15, but is prevented-by therods from extending to any large extent to the part of the filamentslying between rods 15 and'the spinning jet 13. On leaving the roller 32the filaments 14 pass to the balloon guide 33of a cap spinning device31by means of whichthey are twisted, and wound on to a bobbin 35. IFigure 2 shows a variation in detail of the upper part'of the cell shownin Figure 1. In this figure ahood is provided around the jet 13 in theform of a'single piece 37 which is fitted with aflexible tubing38'controlled by a valve 39 lying outside the cell. By means of the tube38 a proportion'of air, preferably small, may be drawn Off from the hood37, or alternatively a small quantity of 'air may be passed into thecell by the same means. Or again, the stagnant nature of the'atmospherewithin the hood 37 may be augmented by supplying through the tube 38vapours of material which is a solvent for the substance of thefilaments,'e. g. the solvent which is used in the spinning solution fromwhich the filaments are produced. v I

In Figure 3 a current of evaporative medium enters the spinning cell 10through an annular pipe '41, fed by a pipe 42 and valve 43 from apressure header 44 or other supply. The current of evaporative mediumfiows in the same direction as the filaments and leaves by a draw-offdevice 45 atthe bottom of the cell 10, the drawoff device being providedwith control means indicated diagrammatically at'fi. Since the annularpipe 41 through which evaporative medium is introduced into the celllies below the level of the nozzle 13, that part of the cell lying abovethe ringl, including the nozzle 13, is not swept by thecurrent ofevaporative medium and, in consequence, evaporation therein is retarded.In

orderto protect the filaments 14; as they issue from the nozzle 15 fromsmallirregular currents of evaporative medium, a hood 47'is providedabout the nozzle 13. Stretchis applied tothe filaments 14 lying withinthe cell in a manner similar to that described with reference to Figure1, the stretch being prevented frorrrrunriing back to the filaments 14in the neighbourhood of the nozzle 13 by means of tension rods 15 in-andout of which the filaments pass.

Figure 4 shows the evaporative medium entering at the bottomofthe cell,as described with reference to Figure l, and leaving by an-annular tube50 lying below the level of the spinning nozzle 13. 'Adraw-oif pipe 51leads from thaanjnular pipe 50 out of the cell and is provided withcontrol means similar to those describedwith'ref erence to Figure 1. Thenozzle 13 and the filaments immediately issuing therefrom are containedin a separate chamber. 52divided from the rest of the spinning cell 10by means of a partition.53. Since the major part of-the evaporativemedium is drawn off before entering the chamber 52, evaporation of thefilaments therein is retarded. An additional draw-off device 54 may beprovided in the chamber 52 whereby a slow current of evaporative mediummay be caused 'to' I pass through thechamber 52, so that the-stagnantnature of the atmosphere in the chamber may be modified at will; Theproportion of evaporative mediumleaving the cell in this manner may becontrolled by means similar'to those 1 described in connection with thedraw-off device 21 in Figure 1. As described with reference to Figures 1to 3 stretch applied to the filaments 14 outside the cell 10 isprevented'fro'm running back to the nozzle 13 by means of tension bars15 in and out of which the filaments pass.

In Figure 5 the restriction of evaporation is efiected in the mannerdescribed with reference to Figure 1, a hood 56' being provided roundthe spinning jet 13 for this purpose. The filaments l4 issuing from thehood 56 pass successively round two rollers 57, 58 inside the cellbefore turning round the guide 16 and leaving the cell by the orifice17. The filaments then pass over a feed roller 32 driven at a constantperipheral speed, the roller 58 being drivenfrom the roller 32 by meansof a chain 60 and gears 61, 62. The peripheral speed of the roller 58 islower than that of the roller 32 so that the filaments 14 are stretchedbetween them, the filaments being softened by passage over a wick 59supplied with a solvent or the like. The roller 57 is provided with ahand brake 63 adjustable by means of a spring 64 and a wing nut 65, theeffect of the braked roller being to allow stretch to be imparted to thefilaments 14: between the rollers 57,

58 and to prevent such stretch from-being communicated beyond the roller57 to the filaments 14 lying between it and the jet 13. The filaments 14leaving the roller 32 pass to a cap spinning device as described withreferenceto Figure 1, or to any otherlconvenient collecting means (notshown). 7 i

Figure 6 shows an alternative form of braking device for the roller 57,the shaft 67 on which the roller is mounted extending outside the cell10 and being provided with a metal disc 68 rotating between the poles ofa magnet 69 excited by means of a coil 70. In this manner a resistanceto rotation is imparted to the shaft 6'7 and :the

roller 57, similar to that imparted-by the brake 63 shown in Figure 5.The disc 68- and the magnet 69 may be of such size as to serve a seriesof rollers 5'7 rotating in a series of cellsand mounted on a commonshaft 67 running along the length of the series, so'that uniformity inthe manner-of applying stretchis ensured throughfrom the effect of themain body of such current so asto retard its initialevaporatiomsubmitting the product to a stretching'operation, andrestraining the-stretch so imparted so that .the whole of itdoes notextend to the part 'ofthe product. so secluded. V

'2. Process for the production ofartificial fila-' ments,x'threads,yarns, ribbons and the like by the dry .or evaporative :method, whichprocess comprises lextruding a spinning solutioninto a current ofevaporative medium flowing pastlthe point .of extrusion, secluding theextruded prod uct in the initial stages of spinning from the effect ofthe main body of such currentxso as to retard its initialevaporation,'submitting the productv to a, stretching operation, andrestraining'the stretch 1 ments, threads, yarns, ribbons and the like bythe dry or evaporative method, which process comprises extruding aspinning solution into a current of evaporative medium flowing. inadirection oppositeto the direction of extrusion, withdrawing saidcurrent of evaporative medium before it reaches the-point of extrusionso as to seclude the extruded product inthe initial stages of spinningfrom the effect of the main body of such current and to retard itsinitial evaporation, submittingthe product to a stretching operation,and restraining the stretch so imparted so that the whole of it does-notextend to the part of the product so secluded.

4. Process for the production of artificial filaments, threads'yarns,ribbons and the like by the dry or evaporative method, which processcomprises extruding a spinning solution into a current or evaporativemedium flowing in the direction of extrusion but originating at a pointon the extrusion side of the point of extrusion so as to seclude theextruded product in the initial stages of spinning from the effect ofthe main body of such current and to retard its'initial ments, threads,yarns, ribbons and the like by the dry or evaporative method, whichprocess comprises extruding a spinning solution'into a current ofevaporative medium, secluding the extruded product in the initial stagesof spinning from the efiect of the main body of such current so as toretard its initial evaporation but al lowing a small quantity ofevaporative medium to flow past the point of extrusion, submitting theproduct to a stretching operation, and restraining the stretch soimparted so thatthe whole of it does not extend to the part of theproduct so secluded.

6.. Process for the production of artificial fila ments, threads, yarns,ribbonsand the like by thedry orevaporative method, which processcomprises extruding a spinning solutioninto-a ments, threads, yarns,ribbons and the like by the dry or evaporativemethod, .which processcomprises extruding a spinning solution into'a current of evaporativemedium flowing in the direction of extrusion but originating mainly atapoint on the extrusion side of the point of extrusion so as to secludethe extruded product in the initial stages of spinning'from theefiect ofthe main body of such current and to retard its initial evaporation,submitting the product to a stretching operation, and restraining the Qstretch so imparted so that the whole of it does not extend to the partof the product so secluded.

8. Process for the production of artificial filaments,threads,.yarns,ribbons and the like by the dry or evaporative method,which process comprises extruding a spinning solution into a current' ofevaporative medium, secluding the extruded product in the initial stagesof spinning from the effect of the main body of such current so as toretard its initial evaporation,

submitting the. product to' a stretching operation, restraining thestretch so imparted so that the whole of it does not extend to the part,of the product so secluded, andintroducing in the neighborhood of theproduct in the initial stages of spinning vapors of a solvent for thesubstance of the product. A

9. Process for the production of artificial filaments, threads, yarns,ribbons and, the like by the dry or evaporative method, which processcomprises extruding a spinning solution containing a high boilingsolvent into a currentof evaporative medium, secluding the extrudedproduct in the initial stages of spinning from the effect of the mainbody-of such currentso as to retard its initial evaporation, submittingthe product to a stretching operation, and restraining the stretch soimparted so that the whole of it does not extend to the part of theproduct so secluded.

10. Process for the productionof artificial filaments, threads,yarns,.ribbons and the like from solutionsof cellulose derivatives bythe dry or evaporative method, which process comprises extruding aspinning solution'of a cellulose derivative intoa current ofevaporativemedium, secluding the extruded product in the initial stagesof spinning from the effect of. the'main body of such current so as toretard its initial evaporation, submitting the product to a stretchingoperation, and restraining the stretch so imparted so that the whole ofitdoes not ex- 1 tend to the part of the product so secluded.-

11. Process for the production of artificial filaments, threads, yarns,ribbons and the like from solutions of cellulose acetate by the dry orevaporative' method, which process comprises extruding a spinningsolution of cellulose acetate into a current of evaporative medium,secluding the extruded product in the initial stages of spinning fromthe effect of the main body of such current so as to retard its initialevaporation, submitting the product to a stretching op-,

eration, and restraining the stretch so imparted sothat the whole of itdoes not extendto the part of the product so secluded.

12. Apparatus for the production of artificial filaments, threads,yarns, ribbons and the like by the dry or evaporative method, whichcomprises a spinning cell, a spinning jet therein for the'extrusion ofmaterial, means for passing a current of evaporativemedium through saidcell, means for secluding the extruded product from they main efiect ofsaid current in the neighborhood of said jet, means for stretching saidproduct and means for preventingthe applied stretch from reaching thesecluded part of said product.

13. Apparatus for the production of artificialfilaments,ithreads,-yarns, ribbons and the like by the dry orevaporative'method, which comprises a spinning cell, a spinning jettherein for the extrusion of material, means for passing a current ofevaporative medium through said cell, a shield. adapted to surround theneighborhood of said jet for secluding the extruded product from themain effect of said current in the neighborhood of said'jet, means forstretching said product and means for preventing the applied stretchfrom reaching the secluded part of said product. p

14. Apparatus for the production of artificial filaments, threads,yarns, ribbons and the like by the dry orrevaporative method, whichcomprises a spinning cell, a spinning jet therein for the extrusion ofmaterial, means for passing a current of evaporative medium through saidcell in a direction opposite to the direction of extrusion, means forwithdrawing said current at a point short of the spinning jet so as toseclude the extruded product from the main effect of said current in theneighborhood of said jet, means'for stretching said product and meansfor preventing the applied stretch from reach-v ing the secluded part ofsaid product.

15. Apparatus for the production of artificial filaments, threads,yarns, ribbons and the like by the dry or evaporative method, whichcomprises a spinning cell, a spinning jet therein for the extrusion ofmaterial, means for passing a current of evaporative medium through saidcell in'the direction of extrusion and froma point on the extrusion sideof said jet so as to seclude the extruded product from the main eirectof said current in the neighborhood of said jet, means for stretchingsaid product and means for preventing the applied stretching fromreaching the secluded part of said product.

16. Apparatus for the production of artificial filaments, threads,yarns, ribbons and the like by the dry or evaporative method, whichcomprises a spinning cell, a spinning jet therein for the extrusion ofmaterial, means-for passing a current of evaporative medium through saidcell, means for secluding the extruded product from the main effect ofsaid current in the neighborhood of said jetymeans for stretching saidproduct, means for preventing the applied stretch from reaching thesecluded part of said product, and means for introducing a smallquantity of evaporative medium to reach the product in the initialstages.

'17. Apparatus for the production of artificial filaments, threads,yarns, ribbons and the like by the dry or evaporative method, whichcomprises a spinning cell, a spinning jet therein for the extrusion of'material, means for passing a current of evaporative medium throughsaid cell.

a shield adapted to surround the neighborhood of said jet for secludingthe extruded product from the main efiect of said current in theneighborhood of said jet, means for stretching said product, means forpreventing the applied stretch from reaching the secluded part of saidproduct, and means for introducing .a small quantity of evaporativemedium within said shield.

18. Apparatus for the production of artificial filaments,*threads,yarns, ribbons and the like by the dry or evaporative method, whichcomprises a. spinning cell, a spinning jet therein for the extrusion ofmaterial, means for passing a current of evaporative medium through saidcell in a direction opposite to the direction of extrusion, means forwithdrawing the greater part of said current at a point short of thespinning jet so as to Seclude the extruded product from the main efiectof said current in the neighborhood of said jet, means for stretchingsaid product, means for preventing the applied stretch from reaching thesecluded part of said product and means for withdrawing the remainder ofsaid current at a point behind said spinning jet.

19. Apparatus for the production of artificial filaments, threads,yarns, ribbons and the like by thedry or evaporative method, whichcomprises a spinning cell, aspinning jet therein for the extrusion ofmaterial, means for passing a current of evaporative medium through saidcell in the direction of extrusion and for the most part from a point onthe extrusion side of the said jet so as to seclude the extruded product7 from the main effect of said current in the neighg borhood of saidjet, means for stretching said product, means for preventing the appliedstretch from reaching the secluded part of said product, and means forintroducing a small current of evaporative-medium at a point behind thespinning jet.

20. Apparatus for the production of artificial filaments, threads,yarns, ribbons and the like by the dry or evaporative method, whichcomprises a spinning cell, a spinning jet therein for the extrusion ofmaterial, means for passing a current of evaporative medium through saidcell, means for secluding the extruded product from the main efiect ofsaid current in the neighborhood of said jet, means for stretching saidproduct, and a plurality of tension rods disposed on the extrusion sideof the spinning jet for preventing the applied stretch from reaching thesecluded part of said product.

21. Apparatus for the production of artificial filaments, threads,yarns, ribbonsand the like by the dry or evaporative method, which com-7 prises a spinning cell, a spinning jet therein for the extrusionof'material, means for passing a current of evaporative medium throughsaid cell, means for secluding the extruding product from the mainefiect of said current in the neighborhood of said jet,a pair of rollerswithin the spinning cell for stzretching'said product, means for drivingthe second of said rollers and means for braking the first of saidrollers so as to prevent the applied stretch from reaching the secludedpart of said product.

HENRY DREYFUS.

